1. Field of the Invention
This invention relates to packaging and containers for microscope slides and to means for dispensing the slides from such containers.
2. Description of Prior Art
Microscope slides are well known as thin rectangular plates of glass on which fluid, tissue smears or other biological specimens may be mounted for examination under a microscope. These slides are manufactured by the millions and are generally sold in shallow cardboard boxes, in which the slides are placed on edge to form a horizontal stack filling the box bottom front to back, the longitudinal side edge of each slide lying on the bottom of the box (i.e., with the side of the stack laid onto the bottom surface of the box). A close-fitting top is then snugly fitted over the filled bottom, and the box is sealed in a wrapper to prevent contamination in transit to the end user.
While due care is usually taken by the manufacturer in preparing and packaging the slides, so that dust, fungal and bacterial spores, and other contaminants are prevented from readily adhering to them, once the box is open at, e.g. a laboratory site, removal of the slides by the end user is most often accomplished merely by grasping a slide and pulling it from the box. The slides are normally used one at a time and the open box with the stack of slides exposed to the laboratory environment is typically left on a table top until it is empty.
This practice leaves the unused slides in the open box exposed to contamination, for example by deposition thereon of aerosol droplets from sprays used in the laboratory, from medical specimen fluids themselves, and from various chemicals and liquids normally used in such laboratories, such as fixative compounds sprayed on specimens being prepared on other slides nearby, disinfectants, water sprays, etc., as well as dust and other airborne materials. Furthermore, even though slides are normally handled by the edges, it is difficult to avoid leaving finger marks in the form of deposited body oils and other substances carried on the fingers of laboratory personnel.
Not only does such handling of the slides promote their contamination--especially if the user's hand is not covered by a sterile glove--but it also subjects the laboratory personnel to the risk of cuts, as the user's fingers can easily slide along the sharp edges of the slides, when force is exerted to pull them from the box. This can happen because the smooth glass surfaces in a stack of slides adhere together rather easily when wetted by moisture or fluid droplets in an open box in the laboratory. As the technical personnel attempts to separate the slides skin cuts can occur rather easily. It should be noted that since economy is a key factor in the manufacture of microscope slides, the slide edges are normally not rounded or beveled, so that very little force is required to cause a finger cut to occur. Needless to say, skin cuts are undesirable in the septic environment of medical laboratories as infection may readily occur.
But because economy of production has been so important, and since packaging of microscope slides in such cardboard boxes has become so universal, little attention has been given to alternative packaging and dispensing. Also, since slides are normally grasped by the edges i.e., with a thumb and index finger placed at opposite sides of the longitudinal dimension of the slide (to remove it from the box) or the transverse direction (to mount the specimen and place the complete slide under the microscope)--it is assumed that little contamination occurs.
While such problems might be reasonably dealt with by careful training and supervision of professional laboratory technologists, these risks impose an additional burden on such personnel who already are under considerable strain because of the need to make careful evaluations of large numbers of medical specimens.
Thus, there is a definite need for some means by which microscope slides may be dispensed as needed from a protected container in a manner which minimizes the possibility of cuts and contamination.
Efforts have been made to solve--or, at least, to minimize--such difficulties by providing microscope slide dispensers which eject slides one at a time from within a protected enclosure. One such dispenser is illustrated in the 1992 Baxter Scientific Catalog as Catalog Number M6180, Manufacturer Nr. 1415, and is priced at US$157.60. This device which is made of sturdy sheet steel has a rectangular container into which a vertical stack of microscope slides can be introduced through a removable side panel such that the lowermost slide in the stack rests upon the bottom of the container. Built into a bottom compartment of the container is an ejection mechanism actuated by an external lever arm mounted on one side of the slide container. Manually depressing the lever arm through an angle of approximately ninety degrees advances an ejector element under the lowermost slide in the stack. The ejector element has an upstanding lip which engages a rear edge of the lowermost slide and pushes the opposite end of the slide through a slot in the side of the container. The protruding end of the slide can then be manually grasped and the rest of the slide pulled from the dispenser. The next lowermost slide then drops to the bottom into position for ejection when the lever is again actuated. While this existing device works well, the actuating lever is spring loaded and its design calls for rugged construction in order to withstand the repeated compression of its internal spring element, and therefore the device is fabricated of steel. While durable and reliable, this device is expensive, and consequently its widespread use--when measured against the typical process of removing slides by hand, one-by-one, from an open cardboard box--has been limited. And, in any event, the entire stack of slides must be still initially be removed from its original cardboard box by hand and then hand-loaded into the dispenser, so that opportunity for contamination still exists.
In another existing microscope slide dispenser the lowermost slide in a stack rests upon a cylinder which can be turned by means of an external knob, ejecting the lowermost slide sideways and edgewise from the stack through a slot in the housing containing the stack as a result of frictional force between the bottom slide and the rotating cylinder surface. This dispensing device has been found to be somewhat unreliable as the cylinder surface wears and diminishes in friction through usage, until it tends to merely slips against the bottom slide in the stack. Again, this dispenser too must be hand loaded with slides taken from a factory package.
What is needed is a simple, less expensive device in which microscope slides may be packaged--or into which they may be easily inserted--and from which they may be removed individually, with minimized susceptibility to contamination of the slide surfaces and a relatively smaller likelihood of finger cuts. In particular a need exists for a slide dispenser which is of sufficiently low cost as to be suitable for use as the original factory packaging for the slides, thereby eliminating the need to transfer the slides to a separate dispenser at a laboratory or other end user location. Optimally, the slide dispenser should be of sufficient simplicity and low cost as to be discardable or recyclable after a single use, so that factory packaged slides may be dispensed one at a time for immediate use in the laboratory, with no intermediate handling or exposure of the slides.